Conventionally, in a sensor network system, numerous radio sensor nodes detect environmental changes in an area in which the sensor nodes are disposed.
According to a known technique, characteristics of sensor data for an area in which a sensor node is disposed are calculated based on data measured at respective sensor nodes and specific information that includes information indicating the respective positions of the sensor nodes, for example, refer to Japanese Laid-Open Patent Publication No. 2012-165249.
According to another known technique, the power consumption of sensor nodes is reduced by grouping nearby sensor nodes and sequentially operating the sensor nodes, for example, refer to International Publication No. 2006/090480.
According to yet another technique, even when communication is not being performed, measurement values obtained by a sensor are accumulated at a sensor node and based on the accumulated information, the measurement values are transmitted, for example, refer to Japanese Laid-Open Patent Publication No. 2005-223497. Further, according to another known technique, a sensor spontaneously performs measurement and a sensor managing apparatus stores to a storage unit, measurement values from the sensor and measurement time information, whereby a change in the measurement values is detected, for example, refer to Japanese Laid-Open Patent Publication Nos. 2003-115093 and 2005-100443. More specifically, for example, according to a known technique, a measurement value for a timing specified by a client is generated based on the measurement time information and the measurement values stored in the storage unit.
Nonetheless, a problem arises in that, for example, when the transmission of measurement values by a portion of the sensor nodes is suspended to suppress power consumption, the precision of abnormality detection decreases.